While playing Baldur's Gate the other day, I stumbled upon an interesting location that I don't think is written about in any other sources: the Ice Island.

From what I gather, this island is supposedly somewhere in the polar regions of either the far north (based off of the in-game log) or the far south (based off of what one of its inhabitants says). I personally would place it in the far south, as the in-game log is written by the Faerūnian player character who would naturally make the assumption that the frigid environment is up north, whereas the people living there would have had more time to ponder their location. This is further backed up by Dezkiel's Scroll, which claims that different "symbols in the sky" could be seen, much like how the night sky of Earth's north and south poles are dramatically different.

As for the nature of the island, some of the inhabitants relate that it seems to occasionally pull in people attempting teleportation over large distances, trapping them in place by draining the bulk of their magical power into the earth. Perhaps it was put in place to dissuade Torilians from developing large-scale means of teleporting across continents, or maybe as a means of keeping individual spellcasters from growing too powerful, maybe something else entirely?

I think the Ice Island would make for an interesting place to use in play, perhaps when players get a bit too comfortable using teleportation spells to send their party all over the planet. According to in-game accounts it is possible to escape using teamwork, which should make for a fun adventure.

I prefer it 'far to the south' if it's in the Realms. I've a theory that it is, in fact, north...but not actually on Toril at all. But there is no real evidence for that other than the discrepancies you noted. I go with it being a pocket plane and have used in once in a game I ran years ago. Now I'm thinking I should use it again.